Richard, many thanks for your informative reply.
I would guess this is the same W Baker who wrote ‘On the Impurities contained in Lead and theirInfluence on its Technical Uses’ in Mining& Smelting Magazine Vol.4 (1863) pp.201-204, which pushed me to ask the question. In this, he does not admit to having done any experiments to remove copper himself, and gives no dates.
I have now found Percy's 'Metallurgy of Lead' (1870) on the internet, and if you mean the description pp.174-176 'Decopperization of lead by zinc', this seems rather an expensive process. Regarding users specifying a particular brand for the job being a tradition - it would seem to have been a sensible policy in this case. Why spend all that time and money when you know you can buy Snailbeach lead with less than 1% copper to make your red lead for the flint glass trade? In Percy, the first large scale experiment in lead decopperization was stated to have been done in 1861, while the West Midlands glessmakers' red lead producers were still buying Snailbeach lead decades later.
J & H Lloyd of Handsworth, who supplied glassmakers' red lead, bought Snailbeach slag lead specially, and this might have been in addition to pig lead. When J & H Lloyd was bought by Best & Lloyd in the 1880s, they then bought Snailbeach flue dust lead. Adkins of Handsworth, a rival, said in 1882 that nothing other than the flue dust lead would do for their work. Snailbeach slag lead and flue dust lead were produced using a Castilian furnace.
Any ideas what advantages these raw materials might have over the general lead?
Any further contributions welcome - Season's Greetings to one and all.
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